Compression check
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Compression check
I am going to change out all spark plugs and COP. It is misfiring really bad and it has 170k miles. The scanner said 1-6 cylinders are misfiring. I noticed there are at least three different COP. So, I am going to change them all. When I take one spark plug out to do compression check, what do I do about the fuel coming in? I don't want it to hydra lock.
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From: Media PA
You can pull the fuel pump fuse to avoid having fuel being injected while doing the check (with all the plugs out and throttle wide open 
).
COPs do not have a life span like plugs, they tend to live very long and single COPs only need to be changed out with new when proven to be failing. Have you moved the COPs from #1 & 6 (the ones identified as missing) around to other cylinders to see if the misses follow those COPs?
New plugs should always also get new boots and springs, old boots will degrade and develop small (almost invisible) cracks the will bleed voltage out causing a miss.
).COPs do not have a life span like plugs, they tend to live very long and single COPs only need to be changed out with new when proven to be failing. Have you moved the COPs from #1 & 6 (the ones identified as missing) around to other cylinders to see if the misses follow those COPs?
New plugs should always also get new boots and springs, old boots will degrade and develop small (almost invisible) cracks the will bleed voltage out causing a miss.
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Originally Posted by WE3ZS
You can pull the fuel pump fuse to avoid having fuel being injected while doing the check (with all the plugs out and throttle wide open ).
COPs do not have a life span like plugs, they tend to live very long and single COPs only need to be changed out with new when proven to be failing. Have you moved the COPs from #1 & 6 (the ones identified as missing) around to other cylinders to see if the misses follow those COPs?
New plugs should always also get new boots and springs, old boots will degrade and develop small (almost invisible) cracks the will bleed voltage out causing a miss.
).COPs do not have a life span like plugs, they tend to live very long and single COPs only need to be changed out with new when proven to be failing. Have you moved the COPs from #1 & 6 (the ones identified as missing) around to other cylinders to see if the misses follow those COPs?
New plugs should always also get new boots and springs, old boots will degrade and develop small (almost invisible) cracks the will bleed voltage out causing a miss.
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Joined: Jul 2010
Posts: 12,049
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From: Media PA
If you are showing an entire bank as missing, I would start inspecting the wiring harness to the COPS on that side.
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